The present invention relates to air filters for vehicle air conditioning systems, and more particularly, to a method and apparatus for setting an alarm to signal a change of the air filter.
Generally, an air-conditioning duct is provided in a vehicle for the purpose of circulating interior air or keeping it at a comfortable level. Air filters are installed in several places of the air-conditioning duct for purifying air flowing into the vehicle.
For purifying the flowing air and maintaining the comfortable air temperature and quality, the air filters should be maintained in an optimized condition and they should be replaced when they do not perform a proper function. In fact, air filters are frequently changed in a seriously polluted area such as an urban area, but in a rural area, there is no need to frequently change the air filters. Generally, the driver determines the time to change the air filters based on mileage of a vehicle. However, changing air filters in this way is not ideal because it is hard to maintain optimum air-cleaning performance for the air filters and there may also arise an additional cost for unnecessary changes.
As a way to overcome the problem, several methods of signaling the need for a change of an air filter have been suggested. For example, the degree of pollution at the front and rear portions of air filter may be measured. Also, signaling a change using a pressure developed when an air filter is blocked or generating sound by installing an orifice in an air filter have been considered. However, these methods of signaling the need for change of an air filter of a vehicle air conditioning system generate problems that increase the number of parts and processes and thus increase cost because a particular sensor must be set or installed.
Embodiments of the present invention to provide methods for setting an alarm to signal the need for a change of an air filter in a vehicle air conditioning system which can inform of the appropriate time when air filters, which are installed for optimal purification of air flow into a vehicle interior, are to be changed without using a particular sensor.
In a preferred embodiment, the time for an air filter change is signaled based on checking operation of the compressor when the quantity of airflow is decreased, using a sensor already installed in a conventional air conditioning system. More preferably, an embodiment of the invention turns on a blocked filter alarm lamp according to the number of compressor cycles, which are associated with a state of the air filter.